Added toolchain support for Apple M1 and made toolchain_type public to allow extensions

[lomeshpatel]

1. Added and registered kubectl_macos_arm64_toolchain
2. Changed the name of kubectl_osx_toolchain to kubectl_macos_x86_64_toolchain and added an alias for backwards compatibility. Also updated the registration.
3. Made toolchain/kubectl package public to allow for extensions for this toolchain_type

#696

[k8s-ci-robot]

Hi @lomeshpatel. Thanks for your PR.

I'm waiting for a bazelbuild member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[fejta]

/ok-to-test

[k8s-ci-robot]

@lomeshpatel: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-rules-k8s-e2e	833f4be	link	true	/test pull-rules-k8s-e2e

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: fejta, lomeshpatel

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• OWNERS [fejta]

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[lomeshpatel]

@fejta I noticed that one of the checks failed, is that expected or do I need to fix something?

Also, can you please point me to the release process? I just would like to have some understanding of when these changes will be available.